The present invention relates to the intravenous administration of nutrients and therapeutic agents to patients and, more particularly, to an apparatus for administering intravenous hyperalimentation.
Ingestion, digestion, and absorption of food and assimilation of resulting substrates into the body cell mass are vital functions of the gastrointestinal tract. These functions may be impaired in a variety of ways. For example, infants born with gastrointestinal abnormalities, adults who develop gastrointestinal diseases, burn or accident victims, cancer patients, etc., may be unable to maintain their nutritional and fluid balance by oral intake. Without proper treatment they may die from starvation and dehydration.
Traditional intravenous feeding, i.e., through relatively small veins in the limbs, has severe limitations. A patient with one of the above described maladies may initially require eight liters or more of intravenous fluid per day with enough fats, proteins, and carbohydrates to meet the body's nutritional requirements and maintain positive nitrogen balance. Beyond three liters per day, however, the excess fluid strains the cardiovascular system. A diuretic may be given so that the kidneys can process the additional fluid. However, this method is dangerous.
Another approach is to increase the concentration of nutrients in the intravenous solutions. However, such solutions cannot be dripped into a relatively small vein in the arm or leg without severe pain coupled with the risk of vein inflammation and/or thrombosis.
In the early 1960's, Dr. Stanley J. Dudrick and his colleagues developed a method of intravenous nutritional support (referred to in the medical profession as a hyperalimentation or total parenteral nutrition) by which normal growth and development as well as a positive nitrogen balance could be maintained. An open ended catheter was threaded through a moderate sized vein such as the subclavian, accessible under the collarbone, and into a very large vein, the superior vena cava. Because of the very large flow of blood through the superior vena cava, a concentrated solution delivered through the catheter is rapidly diluted, thus allowing administration of a high concentration of nutrients without risk of pain, venous inflammation, or thrombosis.
Since Dr. Dudrick's initial work, extensive research and development has been done with intravenous nutritional solutions. It has been possible to supply up to 7000 calories per day intravenously. Different apparatus and methods have evolved for short and long term intravenous therapy. With the latter, the distal end of the catheter is routed subcutaneously to an exit point midway down the anterior wall of the chest. The patient can then couple the catheter to a source of nutrients in the home and thus avoid prolonged hospitalization while still obtaining intensive nutritional therapy.
In our prior U.S. Pat. No. 4,327,722, we disclose the use of a flexible catheter closed at its proximal end but provided with a slit valve in the wall adjacent such end for fluid passage, and which catheter is inserted into a body vessel for feeding fluid to a patient. A silicone rubber sold under the trademark SILASTIC is disclosed as a suitable material for such catheters. As discussed in that patent, catheters of this type are difficult to insert into a patient because of the flexibility of the catheter, and we disclose the use of an internal stiffener such as flexible wire disposed within the catheter to facilitate its insertion.
U.S. Pat. Nos. 2,393,003; 3,128,769; 3,630,198; 3,742,950; 3,890,970; and 4,068,659; British application Nos. 2,064,963A; 2,032,278A; 1,479,396; 1,155,442; and 484,499; and European application No. 0014424, all address the problem of inserting catheters or like elements into a body.
It is an object of the present invention to provide an improved arrangement for inserting a flexible catheter into a patient.
More particularly, it is an object of the invention to provide an arrangement of catheter and inserting stiffener which permits fluid to be passed through or withdrawn from the catheter as the same is inserted into a patient.
Another object is to provide an improved stiffener that may be withdrawn easily from a catheter after it has been inserted without disturbing the position of the catheter.
It is an object of the present invention to provide an extremely flexible and soft closed-end catheter with an internal stiffening member releasably attached and a distal fluid flow adapter such that the proximal end of the stiffener abuts the closed catheter end allowing facile insertion of the soft flexible catheter by pulling the catheter into place and such that fluid may be infused into or body fluids withdrawn from the catheter through the adapter while the internal stiffening member is in place.
It is yet another object of the present invention to provide a catheter construction allowing determination of venous pressure, preferably in the superior vena cava (central venous pressure), of the vessel in which the catheter tip is positioned without allowing blood reflux into the catheter and without the need for additional apparatus or manometers.